Try to predict the 20 (10-team) or 24 (12-team) keepers that’ll be scooped up in your league. With that in mind, you’ll have a list of Round 1 talent that slipped through the cracks and will be available to draft.
If your 1st round pick is early enough, odds are you’ll get one of those top notch guys. If so, don’t keep Julio. You might get him anyway… which means Melvin is the better choice. He’s a huge value in the 5th round of a 2-keeper league.
If you have a late 1st Round pick, it’s a tougher call. Locking up two top RBs with 2nd and 5th round cost is probably the right decision (because of scarcity at the position), but I understand the pull of getting a potential #1 WR at the end of the first.